Controlled atmosphere when sintering a frit to a glass plate

ABSTRACT

A method is described herein for controlling the oxygen level within an oven while sintering a frit to a glass plate where the sintered frit and glass plate are subsequently sealed to another glass plate to form a sealed glass package. Examples of the sealed glass package include a light-emitting device (e.g., organic light emitting diode (OLED) device), a photovoltaic device, a food container, and a medicine container.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to U.S. patent application Ser. No. ______filed concurrently herewith and entitled “Method for Sintering a Frit toa Glass Plate” (Attorney Docket No. SP08-145). The contents of thisdocument are hereby incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a method for controlling the oxygenlevel within an oven while sintering a frit to a glass plate where thesintered frit and glass plate are subsequently sealed to another glassplate to form a sealed glass package. Examples of the sealed glasspackage include a light-emitting device (e.g., organic light emittingdiode (OLED) device), a photovoltaic device, a food container, and amedicine container.

BACKGROUND

Manufacturers of sealed glass packages such as OLED displays (forexample) are constantly trying to improve the manufacturing process tomore efficiently produce the sealed glass packages. One way to improvethe manufacturing process by controlling the oxygen level within an ovenwhen sintering a frit to a glass plate where the sintered frit and glassplate are subsequently sealed to another glass plate to produce a sealedglass package is the subject of the present invention.

SUMMARY

In one aspect, the present invention includes a method for sintering afrit to a glass plate by: (a) providing the glass plate; (b) depositinga frit onto the glass plate; (c) placing the glass plate with thedeposited frit into an oven; (d) sintering the frit to the glass platewithin the oven by: (i) ramping-up a temperature within the oven to apredetermined temperature, where the predetermined temperature is higherthan a glass transition temperature (T_(g)) of a glass in the frit butless than a crystallization temperature of the glass in the frit; (ii)holding the predetermined temperature within the oven for apredetermined time; and (iii) maintaining an oxygen level within theoven at a predetermined level within a range of about 1,200 ppm-22,220ppm while holding the predetermined temperature within the oven for thepredetermined time; and (e) ramping-down a temperature within the oven;and (f) removing the glass plate with the sintered frit from the oven.

In another aspect, the present invention includes a method for sealing aglass package by: (a) providing a first glass plate and a second glassplate; (b) depositing a frit onto the first glass plate, where the fritincludes a glass, a filler and a dispersant vehicle; (c) placing thefirst glass plate with the deposited frit into an oven; (d) sinteringthe frit to the first glass plate within the oven by: (i) ramping-up atemperature within the oven from a first temperature to a secondtemperature by a first ramp rate with a predeterminedtemperature/predetermined time; (ii) holding the second temperaturewithin the oven for a predetermined time, where the second temperatureis high enough to volatize organic ingredients within the dispersantvehicle in the frit but not higher than a glass transition temperature(T_(g)) of the glass in the frit; (iii) ramping-up a temperature withinthe oven from the second temperature to a third temperature by a secondramp rate with a predetermined temperature/predetermined time; (iv)holding the third temperature within the oven for a predetermined time,where the third temperature is higher than the glass transitiontemperature (T_(g)) of the glass in the frit but less than acrystallization temperature of the glass in the frit; (v) maintaining anoxygen level within the oven at a predetermined level located within arange of about 1,200 ppm-22,220 ppm while holding the third temperaturewithin the oven for the predetermined time; (vi) ramping-down atemperature within the oven from the third temperature to a fourthtemperature by a third ramp rate with a predeterminedtemperature/predetermined time; (vii) ramping-down a temperature withinthe oven from the fourth temperature to a fifth temperature by a fourthramp rate with a predetermined temperature/predetermined time; and (e)removing the first glass plate with the frit from the oven; (f) placingthe second glass plate on the frit attached to the first glass plate;and (g) using a sealing device at a predetermined sealing power to heatthe frit such that the frit melts and forms a seal which connects thefirst glass plate to the second glass plate.

In yet another aspect, the present invention includes a sealed glasspackage comprising a first glass plate and second glass plate that areconnected to one another by a transition metal-lanthanide doped glassfrit which formed a seal between the first glass plate and the secondglass plate, wherein the transition metal-lanthanide doped glass frithas a predetermined color and desired oxidation state due to a using an1,200 ppm-22,220 ppm oxygen controlled atmosphere sintering processwhich was performed to attach the transition metal-lanthanide dopedglass frit to the first glass plate before the second glass plate wasplaced on top of the sintered transition metal-lanthanide doped glassfrit and the sintered transition metal-lanthanide doped glass frit wasmelted to form the seal between the first glass plate and the secondglass plate (note: the term transition metal-lanthanide doped glass fritincludes a transition metal doped glass frit, a lanthanide doped glassfrit or a transition metal and lanthanide doped glass frit).

Additional aspects of the invention will be set forth, in part, in thedetailed description, figures and any claims which follow, and in partwill be derived from the detailed description, or can be learned bypractice of the invention. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory only and are not restrictive of the inventionas disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had byreference to the following detailed description when taken inconjunction with the accompanying drawings wherein:

FIGS. 1A and 1B respectively illustrate a top view and a cross-sectionalside view of a sealed glass package in accordance with an embodiment ofthe present invention;

FIG. 2 is a flowchart illustrating the steps of a method formanufacturing the sealed glass package in accordance with an embodimentof the present invention;

FIG. 3 is a graph which is used to help explain the steps of an oxygencontrolled atmosphere sintering process that is used in the method ofFIG. 2 in accordance with an embodiment of the present invention; and

FIG. 4 is graph that illustrates the relationship of the oxygen levelused during a sintering step in the method of FIG. 2 to the sealingpower used during a sealing step in the method of FIG. 2 in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, there are disclosed a sealed glass package 100and a method 200 for sealing the glass package 100 using an oxygencontrolled atmosphere controlled sintering process in accordance with anembodiment of the present invention. The sealing method 200 is describedbelow with respect to sealing a glass package 100 that includes twoglass plates 102 and 110 that are bonded to one another by a frit 108and where the two glass plates 102 and 110 contain one or morecomponents 104. Examples of the sealed glass package 100 include alight-emitting device 100 (e.g., organic light emitting diode (OLED)device 100), a photovoltaic device 100, a food container 100, and amedicine container 100. However, the present invention should not beconstrued as being limited to any specific type of sealed glass package100.

Referring to FIGS. 1A and 1B, there are respectively shown a top viewand a cross-sectional side view illustrating the basic components of thesealed glass package 100 in accordance an embodiment of with the presentinvention. The sealed glass package 100 includes a first glass plate102, one or more components-electrodes 104 and 106 (optional), a frit108 and a second glass plate 110. The sealed glass package 100 has aseal 112 (e.g., hermetic seal 112) formed from the frit 108 whichcontains and protects the one or more components 104 (if present)located between the first glass plate 102 and the second glass plate110. The electrode(s) 106 (if present) are connected to the component(s)104 and also pass through the seal 112 so they can be connected to anexternal device (not shown). The seal 112 is typically located aroundthe perimeter of the glass package 100 such that the component(s) 104(if present) and at least a part of the electrode(s) 106 (if present)are located within the perimeter of the seal 112. How the glass package100 is manufactured using the oxygen controlled atmosphere sinteringprocess and the ancillary components such as the sealing device 114(e.g., laser 114 and/or infrared lamp 114) are described in greaterdetail below with respect to FIGS. 2-4.

Referring to FIG. 2, there is a flowchart illustrating the steps of themethod 200 for manufacturing the sealed glass package 100 in accordancewith an embodiment of the present invention. Beginning at steps 202 and204, the first glass plate 102 and the second glass plate 110 areprovided so that one can make the sealed glass package 100. In oneembodiment, the first and second glass plates 102 and 110 aretransparent glass plates such as soda lime glass plates oralkaline-earth alumino borosilicate glass plates like the onesmanufactured and sold by Corning Incorporated under the brand names ofCode 1737 glass, Eagle 2000™ glass, and Eagle XG™ glass. Alternatively,the first and second glass plates 102 and 110 can be transparent glassplates like the ones manufactured and sold by companies such as AsahiGlass Co. (e.g., OA10 glass and OA21 glass), Nippon Electric Glass Co.,NHTechno and Samsung Corning Precision Glass Co. (for example). Ifdesired, either or both of the glass plates 102 and 110 could benon-transparent. In addition, the glass plates 102 and 110 could have acoefficient of thermal expansion (CTE) in the range of 30-110×10⁻⁷ perdegree centigrade (° C.).

At step 206, the frit 108 is deposited along the edges of the firstglass plate 102 in a manner that the frit 108 forms a closed-loop on asurface of the first glass plate 102. For instance, the frit 108 can beplaced approximately 1 mm away from the free edges of the first glassplate 102. The frit 108 is made from a glass (e.g., glass doped with atleast one transition metal like iron, copper, vanadium, and neodymium),a filler (e.g., inversion filler, additive filler), and a dispersantvehicle. The filler is typically used to lower the coefficient ofthermal expansion (CTE) of the frit 108 so that it matches orsubstantially matches the CTEs of the two glass plates 102 and 110. Inone embodiment, the frit 108 is made of a blend of powderedantimony-vanadate-phosphate glass with β-eucryptite filler that haveparticle sizes on average below 10 μm or, preferably, less than or equalto 3 μm. And, the dispersant vehicle may be a blend of2,2,4-trimethyl-1,3-pentadiol monoisobutyrate (brandname of Texanol) andother dispersants (e.g., Anti-Terra, BYK, Solsperse and ethylcellulose)which do not evaporate quickly and keep the solids in suspension betweenthe time that the frit 108 is dispensed onto the first glass plate 102until it is sintered. The compositions of several different exemplaryfrits 108 which could be used in this particular application with theaddition of the dispersant vehicle have been discussed in a co-assignedU.S. Pat. No. 6,998,776 entitled “Glass Package that is HermeticallySealed with a Frit and Method of Fabrication”. The contents of thisdocument are hereby incorporated by reference herein.

At step 208, the first glass plate 102 with the deposited frit 108 isplaced into an oven. In one embodiment, the oven can heat-up totemperatures of 400-450° C. while located in a clean room (e.g., Class1000 clean room). The oven can be electric or gas fired (typicallynatural gas) and can be made by various manufacturers such as, forexample, Blue M, Lindbergh, Glenro, Despatch, HIX, Smit, Thermatrol,Epcon Industrial Systems, Gruenberg, Intek, and Lewco. An electric ovenis desirable since it is much cleaner than a gas fired oven. Theelectric oven can utilize resistance heating elements to heat the airand transfer that energy via a convection type heating to the frit 108and glass sheet 102. Another type of oven that could be used utilizesinfrared heating to directly heat the frit 108 and glass sheet 102. Infact, some ovens can use different combinations of these heating methodsto heat the frit 108 and glass sheet 102. Alternatively, continuous typesintering ovens with belts, pushers and lehrs can be used to heat thefrit 108 and glass plate 102. The continuous type sintering ovens wouldhave different zones through which the frits 108 and glass plates 102would travel.

At step 210, the frit 108 is sintered to the first glass plate 102 whilewithin the oven where the frit 108 is heated and becomes attached to thefirst glass plate 102. In particular, the frit 108 is sintered to thefirst glass plate 102 using an oxygen controlled atmosphere sinteringprocess in accordance with an embodiment of the present invention whichtakes less than 8 hours, preferably less than 6 hours and morepreferably less than 3.25 hours. The exemplary oxygen controlledatmosphere sintering process 210 has multiple steps where first thetemperature within the oven is ramped-up from a first temperature to asecond temperature, where the second temperature is high enough tovolatize organic ingredients within the dispersant vehicle of the frit108 but not higher than a glass transition temperature (T_(g)) of theglass in the frit 108. The second temperature is held for apredetermined time and before the end of the predetermined time an inertgas supply (e.g., N₂ gas supply, He gas supply) or a reducing gas supply(e.g., H₂ gas supply) is turned-on to displace a desired amount of theair located within the oven (step 210 a). Second, the temperature withinthe oven is ramped-up from the second temperature to a thirdtemperature, where the third temperature is higher than the glasstransition temperature (T_(g)) of the glass in the frit 108 but lessthan a crystallization temperature of the glass in the frit 108. Thethird temperature is held for a predetermined time while at the sametime maintaining an oxygen level within the oven at a predeterminedlevel somewhere within a range of about 1,200 ppm-22,220 ppm (step 210b). Thirdly, the temperature within the oven is ramped-down at apredetermined rate to prevent the cracking of the first glass plate 102with the sintered frit 108 (step 210 c). If desired, the sintered frit108 can be ground to reduce its thickness variation to less than 5-10 μm(for example). An alternative oxygen controlled atmosphere sinteringprocess 210 that can be used in this particular application is describedbelow with respect to several experimentally tested glass packages 100.Of course, the alternative oxygen controlled atmosphere sinteringprocesses 210 can be implemented to make other types of sealing glasspackages 100 and not just the experimentally tested glass packages 100.

At step 212 (optional), the components 104 (e.g., OLEDs 104, food 104,medicine 104) and associated electrodes 106 (if needed) are depositedonto the second glass plate 110. This step can be omitted if the sealedglass package 100 is not supposed to contain components-electrodes 104and 106 but instead will contain only a liquid or gas.

At step 214, the second glass plate 110 is placed on the frit 108 thathas been attached to the first glass plate 102. For instance, the secondglass plate 110 can be placed on top of the frit 108 attached to thefirst glass plate 102. Or, the first glass plate 102 with the attachedfrit 108 can be placed on top of the second glass plate 110.

At step 216, the frit 108 may be heated by the sealing device 114 (e.g.,laser 114, infrared lamp 114) in a manner such that the frit 108 meltsand forms the seal 112 (e.g., hermetic seal 112) which bonds the firstglass plate 102 to second glass plate 110 (see FIG. 1B). In addition,the seal 112 protects the component(s) 104 (if any) by preventing, forexample, oxygen and moisture located in the ambient environment fromentering into the sealed glass package 100. Typically, the frit 108contains a glass doped with one or more transition metals (e.g.,vanadium, iron) and/or a lanthanide (e.g., Nd) so as to enhance itsabsorption property at the specific wavelength (e.g., 810 nm wavelength)of the light 116 (e.g., laser beam 116) emitted from the sealing device114 (e.g., laser 114) (see FIGS. 1A-1B). This enhancement of theabsorption property of the frit 108 means that the emitted light 116will be absorbed better by the frit 108 so it will be heated and softenand form the seal 112 (hermetic seal 112). In contrast, the glass plates102 and 110 should be chosen such that they do not absorb much, if any,irradiation from the sealing device 114. Thus, the glass plates 102 and110 would have a relatively low absorption at the specific wavelength ofthe light 116 which would help to minimize the undesirable transfer ofheat from the forming seal 112 (hermetic seal) to thecomponents-electrodes 104 and 106 (if present).

If desired, the sealing device 114 can be used to emit a light 116 thatheats the frit 108 in a manner where a substantially constanttemperature is maintained in the frit 108 along a sealing line 118 thathas regions free of electrodes 106 and regions occupied by electrodes106 (if used) while the frit 108 melts and forms the seal 112 whichconnects the first glass plate 102 to the second glass plate 110. Thiscan be accomplished even if the electrodes 106 absorb or reflectirradiation from the light 116. The constant temperature sealingtechnique is described in a co-assigned U.S. Pat. No. 7,371,143 entitled“Optimization of Parameters for Sealing Organic Emitting Light Diode(OLED) Displays”. The contents of this document are hereby incorporatedby reference herein.

Referring to FIG. 3, there is a graph which is used to help explain anexemplary oxygen controlled atmosphere sintering process 210 that can beused to sinter a frit 108 to the first glass plate 102 in less than 3.5hours in accordance with an embodiment of the present invention. Priorto discussing the oxygen controlled atmosphere sintering process 210, itshould be understood that an experiment is described below where thefrit 108 had a specific composition and the first glass plate 102 had aspecific composition but it should be appreciated that different typesof frits 108 and different types of glass plates 102 could be attachedto one another using the present invention. In addition, the followingexperiment involved the use of particular steps and a particularsequence of steps but it should be appreciated that any of these stepsor the particular sequence of steps may or may not be implemented toattach a frit 108 to a glass plate 110 using the present invention.Accordingly, the oxygen controlled atmosphere sintering process 210should not be construed as being limited to a specific type of frit 108,a specific type of glass plate 102, a specific step, or a specificsequence of steps.

The following explains the experimental procedure that was used to testan exemplary oxygen controlled atmosphere sintering process 210 of thepresent invention. The different procedural steps where as follows:

1. Melt Sb-V-phosphate glass and then melt and crystallize theβ-eucryptite which is used as the filler. The Sb-V-phosphate glass hadthe following composition (mol %): Sb₂O₃: 23.5%, V₂O₅: 47.5%, TiO₂: 1%,Al₂O₃: 1%, Fe₂O₃: 2.5% and P₂O₅%: 27%.

2. Grind the Sb-V-phosphate glass and the β-eucryptite filler to atargeted particle size distribution, in these tests, ≦3 um for the glassand 3 um-7 um for the filler.

3. Blend the powders, by weight, 70% Sb-V-phosphate glass and 30%β-eucryptite filler.

4. Make the dispersant vehicle from a blend of 80.5 wt % Texanol+6.5 wt% each of Anti-Terra 202, BYK 354, Solsperse 900+ethylcellulose added ontop.

5. Mix the dispersant vehicle and powder blend to make a frit paste 108.

6. Dispense the frit paste 108 into nine orthogonal patterns on a 6″×6″Eagle 2000™ glass plate 102 (see step 206 in FIG. 2).

7. Place the dispensed frit paste 108 and the glass plate 102 into anoven (see step 208 in FIG. 2).

8. Sinter the dispensed frit paste 108 to the glass plate 102 using thefollowing exemplary oxygen controlled atmosphere sintering process 210:

a. Heat 25° C.-325° C. by a ramp rate of 10° C./minute (cumulativetime=0.5 hrs) (see step 302 in FIG. 3). This ramp rate is limited by thefurnace design and the thermodynamics associated with transferring heatto the glass plate 102 and the frit 108.

b. Hold 1 hour (in air) and 8 minutes (N₂ on) at 325° C. (cumulativetime=1.6 hrs) (see step 304 in FIG. 3) (note: for the 8 minutes areducing gas (like hydrogen) or an inert gas (like nitrogen) can be usedwhere the inert gas, rather than reducing the frit paste 108, helps toprevent the transition metal-lanthanide from being oxidized by theoxygen in the air).

c. Heat 325° C.-400° C. by a ramp rate of 10° C./minute (cumulativetime=1.75 hrs) (see step 306 in FIG. 3).

d. Hold 1 hour at 400° C. (cumulative time=2.75 hrs) (see step 308 inFIG. 3). In this experiment, the oxygen level content within the ovenwas maintained at a predetermined level within a range of about 1,200ppm-22,220 ppm. The following oxygen levels have been tested: 1,200 ppm(0.12%), 7,400 ppm (0.74%) 22,000 ppm (2.2%), 57,000 ppm (5.7%) and210,000 ppm (21%) (see FIG. 4).

e. Cool 400° C.-300° C. by a ramp rate of 6° C./minute while keeping theoxygen level constant (cumulative time=3 hrs) (see step 310 in FIG. 3).

f. Cool 300° C.-60° C. (N₂ off, full air on for cooling) by a ramp rateof 16° C./minute (cumulative time=3.25 hrs) (see step 312 in FIG. 3).

9. Remove the sintered frit 108 and glass plate 102 from the oven.

10. Seal the sintered frit 108 and glass plate 102 to the other glassplate 110 to form the sealed glass package 100 (see step 216 in FIG. 2).In this case, the sealing device 114 (e.g., 810 nm sealing device 114)and associated components had been located in a Class 1000 clean room.Typically, the frit sealing step 216 can be performed under differentconditions but in this set-up if the sintered frit 108 is sealed at highspeed (e.g., 10-50 mm/minute) and low power (<37 W), then the frit seal112 will likely be hermetic. The frit sealing conditions are alsodependent upon the specific equipment (e.g., sealing device 114) butprocesses can be developed for determining the optimum sealing power andspeed under testing conditions which can then be used in themanufacturing conditions.

The exemplary oxygen controlled atmosphere sintering process 210 (steps8 a-8 f) is described in more detail next to help further explain whythese temperatures and times had been used with this particular frit 108and glass plate 102. The lower hold temperature of 325° C. associatedwith step 304 was selected to volatilize the organic ingredients of thedispersant vehicle while remaining below the T_(g) of the frit's glasssuch that the glass does not flow on top of the glass plate 102. Thehold time of 1 hour and 8 minutes associated with step 304 (which couldbe shortened) was selected to give the dispersant vehicle time tovolatilize and burn off organic components that are used to suspend theglass frit components for the dispensing step 206, and during the last20 minutes, the N₂ supply is turned on so that N₂ at least partiallydisplaces the air before the top temperature (e.g., glass T_(g)) isreached in step 306. The N₂ helps to prevent the oxidation of thevanadium (or other transition metal or lanthanide) in the frit's glassfrom the oxygen in the air so that the glass is durable and has anenhanced absorption property at the specific wavelength (e.g., 810 nmwavelength) of the light 116 (e.g., laser beam 116) emitted from thesealing device 114 (e.g., laser 114). Alternatively, a reducing gas likehydrogen can be used instead of the inert gas to reduce the vanadium (orother transition metal or lanthanide) in the frit's glass so that theglass is durable and has an enhanced absorption property at the specificwavelength (e.g., 810 nm wavelength) of the light 116 emitted from thesealing device 114.

The higher hold temperature at step 308 was 400° C. but it could bebetween 385° C. and 415° C. to avoid a problematical devitrification ofthe frit 108. The hold time at step 308 was set at 1 hour, butadditional experiments have shown that this hold time could be ≦30minutes. In fact, the ramp rates and holds aspects of this exemplarysintering process 210 (steps 8 a-8 f) were generally set in view of theoven design, load in the furnace, and physics of conduction to transferheat from the glass plate 102 to the frit 108. If desired, the ramprates and hold times could be changed to be slower and sometimes faster.

At the higher hold temperature of step 308, the oxygen level contentwithin the oven is preferably maintained at a predetermined levelsomewhere within a range of about 1,200 ppm-22,220 ppm in accordancewith an embodiment of the present invention. The minimum range of 1,200ppm of oxygen was established because there are drawbacks for usingoxygen levels less than this at say 50 ppm-1000 ppm during the sinteringstep 210 even though these extremely low oxygen levels would work tocontrol the vanadium oxidation state in the exemplary vanadium-dopedglass frit 108 which helps control how well the sintered frit 108absorbs the 810 nm light 116 that is emitted from the sealing device114. Some of the drawbacks associated with the use of these extremelylow oxygen levels are as follows:

-   -   It is technically difficult to displace all of the air in an        oven with N2 to reduce the O₂ level to be below 1000 ppm.    -   Extremely low O₂ levels require expensive and exacting sintering        ovens and equipment which basically need to be able to keep the        air out.    -   Extremely low O₂ levels require the use of expensive bottled        ultra-pure N₂ (or other inert gas such as He or reducing agents        such as forming gas or H₂) since this is what would be needed to        displace the air which is used in the first half of the        sintering schedule 210 (steps 8 a-8 b). The less expensive        “house” N₂ may not be used in the extremely low oxygen levels        since it may not be pure enough to displace the air that is used        in the first half of the sintering schedule 210 (steps 8 a-8 b).        Plus, the use of expensive bottled ultra-pure N₂ also require        additional handling which would not be needed if the less        expensive “house” N₂ could be used like it can in the present        invention where the higher oxygen level content of about 1,200        ppm-22,220 ppm is maintained.

Thus, the higher oxygen level content of about 1,200 ppm-22,220 ppm ispreferable and it also appears to result in the formation of a good seal112 (hermetic seal 112) within the sealed glass package 100 (see TABLE#1). The particular oxygen level content (which directly relates to thelevel of the inert gas or reducing agent, i.e. N₂, where the more O₂then the less N₂ and vice versa) that is used within the oven isimportant since it helps control the V oxidation state in the exemplaryvanadium-doped glass frit 108 which helps control how well the sinteredfrit 108 absorbs the 810 nm light 118 (or other light such as 913 nm)that is emitted from the sealing device 114. Generally, the desiredoxygen level content within the oven can be selected based on the typeof sealed glass package 100 that is being manufactured. For instance, ifone is manufacturing a sealed glass package 100 with higher temperaturelead components 104, then this manufacturer could tolerate highersealing power (resulting in higher temperature) and as such higheroxygen levels can be used in the sintering step 210 to reducemanufacturing costs. However if one is manufacturing a certain sealedglass package 100 that has low temperature lead components 104, then onewould want to spend more money to obtain low oxygen levels duringsintering step 210 to be able to have a subsequent sealing step 216 withthe lowest possible power and temperature.

Referring to FIG. 4, there is a graph that illustrates the relationshipof the oxygen level in the sintering step 210 to the sealing power inthe sealing step 216 that was determined by an experimental analysis inaccordance with an embodiment of the present invention. The indicatedoxygen level is a result of averaging 60 measurements that were takenonce a minute during the one hour hold at 400° C. in the sinteringprocess 210 (step 8 d). The highest value of 21% is the O₂ that is inair (the N₂ was not turned on during that run). The sealing power isthat which is determined to exhibit the best seal quality with the maincriterion being a seal width ≧75% of the frit 108. However, it should beappreciated that the seal width ≧75% is not required for a good seal solong as the seal width is continuous around the path of the frit 108.Each optimum sealing window is about +1 watt. In generating thesemeasurements, the sealing conditions were the same for each of the runs(10 mm/sec speed, defocus 7.6 mm beam shape, 810 nm wavelength, roundmagnets applied force to both glass plates 102 and 110, the laserstart/stop, etc.). Only the sealing power was changed for the sealingdevice 114 which was an 810 nm laser diode 114. The same frit, glasssheet type, frit profile, deposition speed, pattern on the 6″×6″ glasssheets, etc. were also used, and all of the samples were dispensedconsecutively (randomized for the runs) when obtaining this information.At the conclusion of this experiment, it was seen that there was nosignificant difference between the sealing power and the seal qualityfor an O₂ level between 1,200 ppm (0.12%) and 22,220 ppm (2.2%). Thissignifies the following:

1. Rather than needing extremely low oxygen content in the range of 50ppm (0.005%) during the sintering step 210 the O₂ level can in fact beas high as 22,200 ppm (2.2%).

2. The seal quality was good for the entire range of O₂.

3. The linear relationship of O₂ with sealing power enables themanufacturer to predict what the sealing power will be as a function ofthe O₂ level or vice versa where the sealing power=0.4(% O₂)+29 whilethe 29 is the y-intercept for this experimental data, it could begeneralized as the lowest sealing power for the lowest O₂ level.

4. The higher O₂ (more air) level means there will be lower operatingexpenses for energy when operating the oven.

5. The larger range of O₂ levels loosens the manufacturing specificationwhich makes it easier to make the sealed glass packages 100.

6. Knowing the O₂ level's impact on laser sealing power needed for aproper seal 112 allows the manufacturing personnel to customize theequipment for a particular sealed glass package 100.

7. The higher O₂ level does not adversely affect the quality of the fritseals 112 in the sealed glass packages 102. In these experiments, it wasfound that the hermetic frit seal 112 in the sealed glass package 100that was made using an 810 nm sealing device 114 had a dark brown colorwhich was found to be indicative of an efficient and cohesive seal. Itis believed the hermetic seal 112 has a dark brown-black colored frit108 because of the presence of a reduced vanadium species such as V⁺³ inthe frit 108 that is caused by the non-oxidizing or reducing conditions(through the use of an inert gas or reducing gas) during sintering. Asdiscussed above, the reduced vanadium species absorbs more 810 nm light118 from the sealing device 114 than a non-reduced vanadium species inthe frit 108.

8. The higher level of O₂ permits the oven to be of a different typethan is needed with the extremely low oxygen level. For example, theextremely low oxygen level requires the use of a specifically designed,tightly sealed inert gas type oven whereas the higher level of oxygenpermits the use of a less expensive more standard designed electric, gasor infrared oven. Plus, the higher level of oxygen permits the use of acontinuous type sintering oven with belts, pushers and lehrs that can beused to sinter the frit 108 and glass plate 102. For instance, thecontinuous type sintering oven can have two different zones throughwhich the frits 108 and glass plates 102 travel where there is one zonewith enough oxygen (˜20%) to completely burnout the organic binder usedto dispense the frit 108 (see step 206) and another zone with a loweroxygen level used to sinter the frit 108 and glass plate 102 (see step210). The higher oxygen levels associated with the sintering step 210 ofthe present invention allows for less expensive, simpler and shortercontinuous type furnaces.

9. The higher level of O₂ permits the oven to be larger which isdesirable if the sintering process 210 is a batch process. Plus, thelarger oven is desirable since the atmosphere therein can replenishedregularly and circulated as the frits 108 and glass plates 102 areheated, and it does not need to be as carefully controlled as would beneeded if there was an extremely low oxygen content which means it isnot easily subject to an “upset” which would disrupt a manufacturingprocess and add cost since the fritted glass plates would have to bediscarded.

The results of the particular experiment associated with FIG. 4 are asfollows:

TABLE #1 Oygen Optimum Level at Laser Sealing Sealing SinteringWavelength Speed Defocus Power Step (%) Laser Type (nm) (mm/sec) (mm)(W) 0.12 Laser Diode 810 20 7.6 29 0.12 Laser Diode 810 20 7.6 29 0.12Laser Diode 810 20 7.6 29 0.12 Laser Diode 810 20 7.6 29 0.12 LaserDiode 810 20 7.6 29 0.74 Laser Diode 810 20 7.6 29 0.74 Laser Diode 81020 7.6 29 2.22 Laser Diode 810 20 7.6 30 2.22 Laser Diode 810 20 7.6 302.22 Laser Diode 810 20 7.6 30 2.22 Laser Diode 810 20 7.6 30 2.22 LaserDiode 810 20 7.6 30 5.75 Laser Diode 810 20 7.6 32 5.75 Laser Diode 81020 7.6 32 15.00 Laser Diode 810 20 7.6 35 20.90 Laser Diode 810 10 7.637 20.90 Laser Diode 810 10 7.6 37 20.90 Laser Diode 810 10 7.6 37 20.90Laser Diode 810 10 7.6 37 20.90 Laser Diode 810 10 7.6 37 20.90 LaserDiode 810 10 7.6 37

In this particular experiment the following conditions were followed:

-   -   Sealing Power: 29-37 W    -   Speed: 20 mm/sec (note: the 20.90 samples were sealed at 10        mm/sec.).    -   Beam shape: Its thermal profile is a parabola, with its maximum        centered within the middle of the frit.    -   Wavelength: 810 nm    -   Applied force: a weight is put in the middle of each sample.    -   Laser start/stop: goes onto sample at the same spot that it        leaves the sample.    -   Frit: Sb-V-phosphate glass, β-eucryptite filler, and a        dispersant vehicle that is a blend of        2,2,4-trimethyl-1,3-pentadiol monoisobutyrate (80.5%        wt)(brandname of Texanol) and other dispersants including        Anti-Terra 202 (6.5% wt), BYK 354 (6.5% wt), Solsperse 9000        (6.5% wt) and ethylcellulose (1.5% wt).    -   Glass: Eagle 2000 glass    -   Profile: Mesa    -   Frit Height: 12-16 microns    -   Frit Width: 0.7 mm wide    -   Dispensing speed: 50 mm/sec    -   Pattern Dimension on 6×6: 27 mm×30 mm

Of course, there are many different speeds, powers, wavelengths, fritcompositions, glass types, etc. . . . that could be used in accordancewith an embodiment of the present invention to make a sealed glasspackage 100 which would work just as well as the exemplary experimentalfrit, glass plate, sealing device etc. . . . Accordingly, the presentinvention should not be construed as being limited to any specific typeof frit, glass plate, sealing device etc. . . .

Although multiple embodiments of the present invention have beenillustrated in the accompanying Drawings and described in the foregoingDetailed Description, it should be understood that the invention is notlimited to the embodiments disclosed, but is capable of numerousrearrangements, modifications and substitutions without departing fromthe spirit of the invention as set forth and defined by the followingclaims.

1. A method for sintering a frit to a glass plate, said methodcomprising the steps of: providing the glass plate; depositing a fritonto the glass plate; placing the glass plate with the deposited fritinto an oven; sintering the frit to the glass plate within the oven by:ramping-up a temperature within the oven to a predetermined temperature,where the predetermined temperature is higher than a glass transitiontemperature (T_(g)) of a glass within the frit but less than acrystallization temperature of the glass in the frit; holding thepredetermined temperature within the oven for a predetermined time; andmaintaining an oxygen level within the oven at a predetermined levelwithin a range of about 1,200 ppm-22,220 ppm while holding thepredetermined temperature within the oven for the predetermined time;and ramping-down a temperature within the oven; and removing the glassplate with the sintered frit from the oven.
 2. The method of claim 1,wherein said maintaining step further includes a step of selecting thepredetermined oxygen level in the oven that is within the range of about1,200 ppm-22,220 ppm based on a desired sealing power to be used in asubsequent step to seal the glass plate with the sintered frit toanother glass plate to form a sealed glass package.
 3. The method ofclaim 2, wherein said selecting step further includes a step of using alinear relationship represented by sealing power=0.4 (% O₂)+y-interceptwhere the y-intercept corresponds to the lowest sealing power for thelowest oxygen level when determining the predetermined oxygen levelbased on the desired sealing power.
 4. The method of claim 1, whereinsaid sintering step prior to the ramping-up step further includes stepsof ramping-up a temperature within the oven to a second predeterminedtemperature and holding the second predetermined temperature within theoven for a predetermined time, where the second predeterminedtemperature is high enough to volatize organic ingredients within adispersant vehicle in the frit but not higher than a glass transitiontemperature (T_(g)) of the glass in the frit.
 5. The method of claim 1,wherein the frit includes glass that is doped with at least onetransition metal including iron, copper and vanadium.
 6. The method ofclaim 1, wherein the frit includes glass that is doped with alanthanide.
 7. The method of claim 1, wherein the frit includes powderedantimony-vanadate-phosphate glass, β-eucryptite filler, and2,2,4-trimethyl-1,3-pentadiol monoisobutyrate dispersant vehicle.
 8. Amethod for sealing a glass package, said method comprising the steps of:providing a first glass plate and a second glass plate; depositing afrit onto the first glass plate, where the frit includes a glass, afiller and a dispersant vehicle; placing the first glass plate with thedeposited frit into an oven; sintering the frit to the first glass platewithin the oven by: ramping-up a temperature within the oven from afirst temperature to a second temperature by a first ramp rate with apredetermined temperature/predetermined time; holding the secondtemperature within the oven for a predetermined time, where the secondtemperature is high enough to volatize organic ingredients within thedispersant vehicle in the frit but not higher than a glass transitiontemperature (T_(g)) of the glass in the frit; ramping-up a temperaturewithin the oven from the second temperature to a third temperature by asecond ramp rate with a predetermined temperature/predetermined time;holding the third temperature within the oven for a predetermined time,where the third temperature is higher than the glass transitiontemperature (T_(g)) of the glass in the frit but less than acrystallization temperature of the glass in the frit; maintaining anoxygen level within the oven at a predetermined level within a range ofabout 1,200 ppm-22,220 ppm while holding the third temperature withinthe oven for the predetermined time; ramping-down a temperature withinthe oven from the third temperature to a fourth temperature by a thirdramp rate with a predetermined temperature/predetermined time;ramping-down a temperature within the oven from the fourth temperatureto a fifth temperature by a fourth ramp rate with a predeterminedtemperature/predetermined time; and removing the first glass plate withthe frit from the oven; placing the second glass plate on the fritattached to the first glass plate; and using a sealing device at apredetermined sealing power to heat the frit such that the frit meltsand forms a seal which connects the first glass plate to the secondglass plate.
 9. The method of claim 8, wherein said maintaining stepfurther includes a step of selecting the predetermined oxygen level inthe oven that is within the range of about 1,200 ppm-22,220 ppm based onthe predetermined sealing power to be used by the sealing device to heatthe frit such that the frit melts and forms the seal which connects thefirst glass plate to the second glass plate.
 10. The method of claim 9,wherein said step of selecting further includes a step of using a linearrelationship represented by sealing power=0.4 (% O₂)+y-intercept wherethe y-intercept corresponds to the lowest sealing power for the lowestoxygen level when determining the predetermined oxygen level based onthe desired sealing power.
 11. The method of claim 8, wherein saidsintering step is performed in less than 8 hours.
 12. The method ofclaim 8, wherein said sintering step is performed in less than 6 hours.13. The method of claim 8, wherein said sintering step is performed inless than 3.5 hours.
 14. The method of claim 8, wherein the oven islocated in a clean room.
 15. The method of claim 8, wherein the fritincludes glass that is doped with at least one transition metal, wherethe at least one transition metal is absorbent at a specific wavelengthof light which is emitted from the sealing device.
 16. The method ofclaim 8, wherein the frit includes glass that is doped with alanthanide, where the lanthanide is absorbent at a specific wavelengthof light which is emitted from the sealing device.
 17. The method ofclaim 8, wherein said first holding step further includes the steps oflimiting an air supply and turning on a reducing-inert gas supply inwhich the reducing-inert gas displaces a desired amount of the airwithin the oven.
 18. The method of claim 8, wherein said firstramping-down step further includes the step of maintaining a flow ofreducing-inert gas within the oven.
 19. The method of claim 8, whereinsaid second ramping-down step further includes the steps of turning offa reducing-inert gas supply and turning on an air supply in which airsubstantially displaces the reducing-inert gas within the oven.
 20. Themethod of claim 8, wherein: said first ramping-up step further includesturning on an air supply when the first temperature of about 25° C. andthe second temperature of about 325° C.; said first holding step furtherincludes limiting the air supply after about 1 hour and turning on areducing-inert gas supply for about 8 minutes before performing saidsecond ramping-up step; said second ramping-up step has the secondtemperature of about 325° C. and the third temperature of about 385°C.-415° C.; said second holding step further includes maintaining theflow of the reducing-inert gas to maintain the predetermined oxygenlevel and maintaining the third temperature of about 385° C.-415° C. forabout 0.5-2.0 hours; said first ramping-down step has the thirdtemperature of about 385° C.-415° C. and the fourth temperature of about300° C.; and said second ramping-down step further includes turning offthe reducing-inert gas supply and turning on the air supply with thefourth temperature of about 300° C. and the fifth temperature of about60° C.
 21. The method of claim 8, wherein said sealing device is used toheat the frit in a manner where a substantially constant temperature ismaintained in the frit along a sealing line while the frit melts andforms the seal which connects the first glass plate to the second glassplate.
 22. The method of claim 8, further comprising the step ofdepositing at least one component onto the second glass plate prior toplacing the second glass plate on the frit attached to the first glassplate and prior to using the sealing device to heat the frit to form theseal which connects the first glass plate to the second glass plate. 23.The method of claim 8, wherein said glass package is: an organic lightemitting diode (OLED) device a photovoltaic device; a food container; ora medicine container
 24. A sealed glass package comprising: a firstglass plate; and a second glass plate, wherein the first glass plate andthe second glass plate are connected to one another by a transitionmetal-lanthanide doped glass frit which formed a seal between the firstglass plate and the second glass plate, wherein the transitionmetal-lanthanide doped glass frit has a predetermined color and desiredoxidation state due to a using an 1,200 ppm-22,220 ppm oxygen controlledsintering process which was performed to attach the transitionmetal-lanthanide doped glass frit to the first glass plate before thesecond glass plate was placed on top of the sintered transitionmetal-lanthanide doped glass frit and the sintered transitionmetal-lanthanide doped glass frit was melted to form the seal betweenthe first glass plate and the second glass plate.
 25. The sealed glasspackage of claim 23, wherein said transition metal-lanthanide dopedglass frit which forms the seal has a brown color.